This invention relates to an improvement in a valve of the type described in Australian patent application No. 60,736/80 (U.K. patent No. 2056027) which has been developed primarily for use in association with flexible pipes or conduits to control the rate of fluid flow therethrough, especially in situations where the fluid flowing through the conduit contains highly abrasive materials.
A valve of the type described includes two cylinders arranged parallel to each other with their circumferential surfaces in contact, at least one of said cylinders having a circumferentially extending groove formed in the surface thereof the depth of which varies along its length, said cylinders at the, or each, groove defining an aperture through which, in use, fluid is constrained to pass, whereby upon rotation of said cylinders relative to each other the size of said aperture varies to vary the rate of flow of fluid through said valve.
In said type of valve, the sealing engagement between the cylinders on either side of the groove, is provided by the rolling contact of plain cylindrical surfaces. An object of the present invention is to provide an alternative mode of sealing.